The subject of this paper is stochastic acceleration by plasma turbulence, a process akin to
the original model proposed by Fermi. We review the relative merits of different acceleration …

Current Cherenkov telescopes have identified a population of ultra-high-frequency peaked
BL Lac objects (UHBLs), also known as extreme blazars, that exhibit exceptionally hard TeV …

Blazars are the most violent steady/recurrent sources of high-energy gamma-ray emission in
the known Universe. They are prominent emitters of electromagnetic radiation throughout …

Gamma-ray bursts (GRBs) are short and intense emission of soft γ-rays, which have
fascinated astronomers and astrophysicists since their unexpected discovery in 1960s. The …

We consider the acceleration of energetic particles by Fermi processes (ie, diffusive shock
acceleration, second order Fermi acceleration, and gradual shear acceleration) in relativistic …

Context. Markarian 501 (Mrk 501) is a very high-energy (VHE) gamma-ray blazar located at
z= 0.034, which is regularly monitored by a wide range of multi-wavelength instruments …

Context. We present an extensive study of the BL Lac object Mrk 501 based on a data set
collected during the multi-instrument campaign spanning from 2009 March 15 to 2009 …

Spectral energy distributions (SEDs) and radio continuum spectra are presented for a
northern sample of 104 extragalactic radio sources, based on the Planck Early Release …

1ES 1959+ 650 is a bright TeV high-frequency-peaked BL Lac object exhibiting interesting
features like “orphan” TeV flares and broad emission in the high-energy regime that are …

Aims. We analyse the influence of the stochastic particle acceleration for the evolution of the
electron spectrum. We assume that all investigated spectra are generated inside a spherical …